1. Field of the Invention
The present invention relates to a liquid jetting apparatus which jets a liquid and a cap member.
2. Description of the Related Art
In some of conventional liquid jetting apparatuses having a liquid jetting head for jetting liquid from nozzles, when liquid jetting performance from the nozzles deteriorates due to the mixture of foreign substances, bubble, and the like in liquid channels in the liquid jetting head or due to the drying and thickening of the liquid in the nozzles, suction purge for recovering the liquid jetting performance from the nozzles by forcibly discharging the aforesaid foreign substances, bubble, or thickened liquid from the nozzles can be performed. For example, an ink jet printer described in Japanese Patent Application Laid-open No. 2008-221836 includes: a cap member which comes into close contact with a liquid jetting surface on which nozzles are open; and a suction means connected to a suction port formed in the cap member, and executes suction purge that reduces pressure in the cap member and suck out liquid from the nozzles by driving the suction means while the cap member is in close contact with the liquid jetting surface, to thereby discharge foreign substances, bubbles, and the like in the liquid jetting head together with the liquid.
However, when the cap member is separated from the liquid jetting surface after the suction purge, if the cap member is separated from the liquid jetting surface while keeping the cap member in a parallel posture which the cap member had when in close contact with the liquid jetting surface, the cap member separates from the liquid jetting surface violently since the pressure in the cap member is negative after the suction purge, and this violent movement scatters the liquid around. Further, a state in which the liquid links between the cap member and the liquid jetting surface (bridge) sometimes occurs and a position of this bridge is not constant.
As a liquid jetting apparatus in which the aforesaid scattering of the liquid is suppressed and the formation position of the bridge is made constant when the cap member is separated from the liquid jetting surface, Japanese Patent Application Laid-open No. 2009-190262, for instance, discloses a printer in which a cap member is separated while tilting relatively to an ink jetting surface on which nozzles are open and a bridge of ink is locally formed at a portion, of the cap member, that separates from the ink jetting surface last, whereby the scattering of the ink is suppressed.
However, in the printer described in Japanese Patent Application Laid-open No. 2009-190262, when the ink jetting surface and the cap member become large in accordance with an upsizing of the nozzles aiming at improvement in print quality, printing speed, and the like, an amount of the ink forming the bridge of the ink increases. The bridge of the ink spreads to the nozzle jetting surface, and as for a nozzle disposed near the portion, of the ink jetting surface, from which the cap member separates last, the ink forming the ink bridge is likely to enter this nozzle due to a back pressure when the nozzle is opened to the air after the cap member separates. Such discharged ink is ink discharged with the foreign substances, bubbles, or thickened ink in the liquid jetting head, and is often foaming. Therefore, such ink, when sucked into the nozzle, may possibly have an adverse effect on a subsequent liquid jetting operation.
Further, when the liquid remaining in the cap member is discharged by the sucking means after the suction purge while the cap member is tilted relatively to the ink jetting surface and the ink bridge is formed, if the ink around the nozzle near the portion, of the ink jetting surface, from which the cap member separates last connects with the ink bridge, the ink in the nozzle near the portion from which the cap member separates last is uselessly discharged infectiously with the discharge of the ink in the cap member, which may possibly increase an amount of the discharged ink.